1. Field of the Invention
This invention relates to a four-step process for the production of tetrahydrofuran in improved yield comprising the reaction of propylene with formaldehyde in the presence of silica sand followed by chlorination, cyclization and hydrogenation of the respective intermediates.
2. Description of the Prior Art
The reaction of olefins with aldehydes is known in the art. The "Prins-Reaction", for example, relates to a reaction between an olefin and an aldehyde in the presence of a strong acid. Many variations of this reaction have been advanced to improve the yield of desired products or to alter the reaction to produce more useful products.
U.S. Pat. No. 2,335,027 describes such a reaction in the absence of a catalyst and U.S. Pat. No. 3,574,773 calls for the presence of a base.
U.S. Pat. No. 3,290,395 discloses the chlorination of unsaturated alcohols in the absence of water and in the presence of hydrogen chloride.
Cyclization of chlorobutanols to tetrahydrofuran is known in the prior art. The usual procedure is to treat the chlorobutanol with aqueous or alcoholic base.
German No. 696,725 discloses a process for 3-chlorotetrahydrofuran whereby a vinyl ether alcohol is treated with chlorine and the 3,4-dichlorobutanol formed is subjected to an HCl-split treatment with sodium hydroxide.
U.S. Pat. No. 3,527,770 relates to the reductive dehalogenation of 4-halotetrahydropyrans to tetrahydropyrans by contact with a Group VIII metal compound and hydrogen.